/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
 package org.apache.iotdb.db.query.externalsort;

 import java.io.IOException;
 import java.util.List;
 import org.apache.iotdb.db.query.control.QueryResourceManager;
 import org.apache.iotdb.db.query.externalsort.serialize.IExternalSortFileDeserializer;
 import org.apache.iotdb.db.query.externalsort.serialize.IExternalSortFileSerializer;
 import org.apache.iotdb.db.query.externalsort.serialize.impl.FixLengthIExternalSortFileDeserializer;
 import org.apache.iotdb.db.query.externalsort.serialize.impl.FixLengthTimeValuePairSerializer;
 import org.apache.iotdb.db.query.reader.IPointReader;
 import org.apache.iotdb.db.query.reader.universal.PriorityMergeReader;


 public class LineMerger {

   private String tmpFilePath;
   private long queryId;

   public LineMerger(long queryId, String tmpFilePath) {
     this.tmpFilePath = tmpFilePath;
     this.queryId = queryId;
   }

   public IPointReader merge(List<IPointReader> prioritySeriesReaders)
       throws IOException {
     IExternalSortFileSerializer serializer = new FixLengthTimeValuePairSerializer(tmpFilePath);
     PriorityMergeReader reader = new PriorityMergeReader(prioritySeriesReaders, 1);
     while (reader.hasNext()) {
       serializer.write(reader.next());
     }
     reader.close();
     serializer.close();
     IExternalSortFileDeserializer deserializer = new FixLengthIExternalSortFileDeserializer(tmpFilePath);
     QueryResourceManager.getInstance().registerTempExternalSortFile(queryId, deserializer);
     return deserializer;
   }
 }
